Development and Collaborative Study of a Diluted Acid Mild Extraction Method for Determination of Cadmium in Grain by Graphite Furnace Atomic Absorption Spectrometry.

The traditional pretreatment methods for the determination of cadmium in grain are time-consuming, cost-consuming, and unfriendly to human health and the environment. To eliminate these disadvantages, we developed an accurate, time-, energy- and cost-efficient method for determination of Cd in grain coupled with graphite furnace atomic absorption spectrometry (GFAAS). The optimization conditions of the extraction were achieved, the accuracy was verified and a collaborative study was organized to evaluate the methods. The detection limit and quantification limit were 0.016 and 0.048 μg L-1, respectively. The whole pretreatment time was reduced to 15 min, and there was no significant difference (P >0.05) between the extraction method and the classic pretreatment method. The method proved to be highly consistent with the results of laboratories in different countries, as determined from two international proficiency tests (| Z | ≤0.3). The repeatability, reproducibility, and HorRat values of the collaborative results were 2.7 - 4.9%, 9.4 - 11.7%, and 0.42 - 0.58, respectively. The method of diluted acid mild extraction coupled with GFAAS is efficient, cost-saving, convenient and friendly.